The present invention relates to methods for safening seeds and/or crop plants treated with sterol inhibiting fungicides, ergosterol biosynthesis inhibiting fungicides.
The discovery and development of fungicides which inhibit fungal ergosterol biosynthesis (sterol inhibiting or SI activity) has led to the introduction of compounds which possess a broad spectrum of fungicidal activity and are particularly effective in controlling powdery mildews, rusts, scab, leafspots and the like in a variety of crops. These compounds, most of which also exhibit systemic fungicidal activity, are in general heterocyclic compounds containing one or more heteroatoms in at least one ring. A review article by T. Kato, in Japan Pesticide Information No. 46. (1985), pp 3 -6 identifies twenty-one compounds divided into six heterocyclic groups i.e. pyridines, pyrimidines, imidazoles, triazoles, piperazines and morpholines which exhibit SI activity.
While these fungicides are highly effective for the control of a wide range of fungi, both as foliar sprays and as seed treatments, undesirable phytotoxic effects, such as slowing the rate of emergence and reducing stands of plants when applied as seed treatments have been reported, i.e. P. Phipps, Plant Disease, 69 (11): pp. 1009-2020 (1985); H. Buchenauer et al, Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz (Journal of Plant Diseases and Protection 91 (5): 506-524 (1984)).
In other studies, H. Buchenauer, E. Roehner CA94(25):203812e (Pestic. Biochem. Physoil., 15(1), 58-70) reported that the fungicides, triadimefon and triadimenol, markedly reduced growth of coleoptiles, primary leaves and barley seedlings roots when grown for 7 days in petri dishes in the dark. Gibberellins (A.sub.1, A.sub.3, A.sub.4 A.sub.7, A.sub.9) alleviated growth retardation of primary leaves and coleoptiles induced by the fungicides, whereas fungicide-induced growth retardation of the shoots was partly relieved by kinetin, and IAA did not show any alleviating activity. The fungicides also were found to substantially retard the elongation of shoots of tomato and cotton plants while simultaneous application of gibberellic acid (GA.sub.3) nullified the retardation. The fungicides only slightly interfered with both .alpha.-amylase production of intact germinating barley seed and the GA.sub.3 -induced .alpha.-amylase synthesis in barley endosperm. Both compounds also interferred with sterol metabolism of shoots of barley seedlings when compared with control plants; treatment resulted in lower amounts and altered proportions of C-4,4-desmethyl sterols. Based upon these studies, it was assumed that these fungicides interfer with gibberellin and sterol biosynthesis in barley seedlings, thereby providing for interfering in the seed's and/or crop plant's development as well. Thus, while beneficial fungicidal activity was obtained, phytotoxic effects also were apparent.